[mikethedruid]

That speaker should work fine. To test it, just tap the leads on a 1 1/2 V battery. You should hear clicking in the speaker. I suggest you not use the power supply for the filaments. Get a small 6V motorcycle battery and a cheap charger for it. For the B supplies you can use the power supply if it is well regulated and smooth. I would buy some C or D cells and make 4 C batteries by wiring sets of 3 each in series. This will allow you to cut in 4 1/2, 9, 13 1/2, or 18 volts for the C voltage by adding C batteries in series until you find what works best. I think it will be 18 V, looking at the characteristics of the '71A. The C battery draw is very low, so these batteries should last a very long time.

[Radioroslyn]

Agree with Mike on the A supply. Your borrowed one doesn't make enough current to power your filaments. That is why you are hearing the 60cy hum, the A buss is heavily loaded and the filter can keep up with the load.
As for regulation on the B voltages not very critical. TRF sets don't really have anything that relies on the voltage being very stable. Superhets the B voltage for the local oscillator needs the stable as it will affect the freq.

Terry N3GTE

[Eric]

Here is where I'm at this morning The 60cyc goes away as the voltage goes above 4vdc . The power supply seems to put out the proper voltages with out any problems.
I'm a little puzzled with the voltage readings here they are going from the ant section 
     Heater        Plate     Grid
1     5vdc         87           0        01A
2     5vdc        116         -22     71A
3     5vdc         87           0        01A
4     5vdc         82           0        01A
5     5vdc         87           0        01A
6     5vdc         22           .5       01A
I then hooked up my signal generator to the ant terminal through a .01 cap and set it to 680 (a strong station in this area). Then played with the 2 tuner wheels until I found a static pop then hooked up my ant wire and played with the volume control and the tuner wheels at that point and the station came in, not real loud but you could listen. Not sure what to expect but this might be as good as it gets?

[mikethedruid]

This radio should play very well actually, and pick up all your local stations with decent volume, even with a fairly short antenna and a good ground. The 71 should be in the socket that connects to the speaker output, since it is the final audio amp. The grid voltage on it should be about 17-18 volts according to its data sheet (see above postings). Again, I strongly urge you to trace the wiring of this set, and make a schematic of your circuit. Then check it against the schematic I posted of a typical TRF set. There may be differences, but it will be similar. Once you have done this, showing the colors of the various battery leads and where they come from in the circuit, it will be much clearer where each connects, and how the batteries (or power supply) should be connected. Also, check all your tubes. Make sure they are all good. A very weak tube that still lights will cause you to lose the amplification to the stage, and cause a very low output.

[Eric]

This radio should play very well actually, and pick up all your local stations with decent volume, even with a fairly short antenna and a good ground. The 71 should be in the socket that connects to the speaker output, since it is the final audio amp. The grid voltage on it should be about 17-18 volts according to its data sheet (see above postings). Again, I strongly urge you to trace the wiring of this set, and make a schematic of your circuit. Then check it against the schematic I posted of a typical TRF set. There may be differences, but it will be similar. Once you have done this, showing the colors of the various battery leads and where they come from in the circuit, it will be much clearer where each connects, and how the batteries (or power supply) should be connected.  Also, check all your tubes. Make sure they are all good. A very weak tube that still lights will cause you to lose the amplification to the stage, and cause a very low output.

I will do that.
The 71 is in the socket that the plate is hooked to the speaker it was not originally. I tested the tubes and had one that showed a short and I replaced it.  The grid voltage I show is neg your post just says 17-18v Is that a problem? 

[mikethedruid]

here is a link to the data sheet. http://www.nmr.mgh.harvard.edu/~reese/RC10/RC10-76.GIF  . -22 volts with regard to the to the cathode is actually a bit low if you are running +135 as your plate voltage on the 171 , but should work OK maybe with the lower plate voltage.

[Eric]

here is a link to the data sheet. http://www.nmr.mgh.harvard.edu/~reese/RC10/RC10-76.GIF  . -22 volts with regard to the to the cathode is actually a bit low if you are running +135 as your plate voltage on the 171 , but should work OK maybe with the lower plate voltage.

Mike, from what your telling me my plate voltage is low @ avg 85v. I'm in the process of drawing out the chassis it will take me a bit. 
Eric

[Radioroslyn]

Going form 82 or 85v to 90 isn't going to change anything to terms of the volume. Now if you where going from 100v to 180v on the 71A that would increase the volume some. If you have a pm spkr & output transformer I'd give that a try instead of the horn. The horn may not be working up to it's full potential.
Looks like you have a resistor solder across the gird leak , what value is it?
Back in the '20's the common type the antenna was two poles extend from the two farest point of the roof. A wire extended across both poles and then a down lead to the set. In total about 70-90' and up 35-50' high.

Terry

[Eric]

Going form 82 or 85v to 90 isn't going to change anything to terms of the volume. Now if you where going from 100v to 180v on the 71A that would increase the volume some. If you have a pm spkr & output transformer I'd give that a try instead of the horn. The horn may not be working up to it's full potential.
Looks like you have a resistor solder across the gird leak , what value is it?
Back in the '20's the common type the antenna was two poles extend from the two farest point of the roof. A wire extended across both poles and then a down lead to the set. In total about 70-90' and up 35-50' high.

Terry

I only have about 15' of ant strung in my garage so that may be a problem, in fact I use a signal gen to help me zero in on stations and when hooked to the ant lead I get a boost in volume. That resistor is 330k (all I had) the original Pilotohm 300k is open look as thought they used it as a fuse as it has a glass body.

[Radioroslyn]

Going form 82 or 85v to 90 isn't going to change anything to terms of the volume. Now if you where going from 100v to 180v on the 71A that would increase the volume some. If you have a pm spkr & output transformer I'd give that a try instead of the horn. The horn may not be working up to it's full potential.
Looks like you have a resistor solder across the gird leak , what value is it?
Back in the '20's the common type the antenna was two poles extend from the two farest point of the roof. A wire extended across both poles and then a down lead to the set. In total about 70-90' and up 35-50' high.

Terry

I only have about 15' of ant strung in my garage so that may be a problem, in fact I use a signal gen to help me zero in on stations and when hooked to the ant lead I get a boost in volume. That resistor is 330k (all I had) the original Pilotohm 300k is open look as thought they used it as a fuse as it has a glass body.

Lose that 330K job it's way too low in value and replace it with a 1 or 2megohm. Although it looks like a fuse it isn't. It provides the grid bias for the detector stage. Recheck the origial one with a meter that will read up to 10megs or so. It maybe ok.

Terry

[Eric]

Going form 82 or 85v to 90 isn't going to change anything to terms of the volume. Now if you where going from 100v to 180v on the 71A that would increase the volume some. If you have a pm spkr & output transformer I'd give that a try instead of the horn. The horn may not be working up to it's full potential.
Looks like you have a resistor solder across the gird leak , what value is it?
Back in the '20's the common type the antenna was two poles extend from the two farest point of the roof. A wire extended across both poles and then a down lead to the set. In total about 70-90' and up 35-50' high.

Terry

I only have about 15' of ant strung in my garage so that may be a problem, in fact I use a signal gen to help me zero in on stations and when hooked to the ant lead I get a boost in volume. That resistor is 330k (all I had) the original Pilotohm 300k is open look as thought they used it as a fuse as it has a glass body.

Lose that 330K job it's way too low in value and replace it with a 1 or 2megohm. Although it looks like a fuse it isn't. It provides the grid bias for the detector stage. Recheck the origial one with a meter that will read up to 10megs or so. It maybe ok.

Terry

Terry.
You nailed it! I guess I'm more dyslexic than I thought the Pilotohm says 3.meg I was seeing .3 meg,  Vol  is good sill not use to using  three controls to find the stations. Thanks

Eric

[Radioroslyn]

Glad to help out  [Image: http://philcoradio.com/phorum/images/smi...iggrin.gif] !
On to the next.

Terry N3GTE